# US 11,442,076 B2 · System and method for wind flow turbulence measurement by LiDAR in a complex terrain

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- Number: US 11,442,076 B2
- Document ID: US11442076B2
- Status: Granted
- Kind: B2
- Application number: 16/838,161
- Filed: 2020-04-02
- Published: 2021-10-07
- Granted: 2022-09-13
- Earliest claimed: 2020-04-02
- Assignees: Mitsubishi Electric Research Laboratories, Inc.
- Applicants: Mitsubishi Electric Research Laboratories, Inc.
- Inventors: Saleh Nabi
- Web page: https://patentgrep.com/patent/US11442076B2

## CPC

- G01P 5/001: {Full-field flow measurement, e.g. determining flow velocity and direction in a whole region at the same time, flow visualisation}
- G01S 13/58: Velocity or trajectory determination systems; Sense-of-movement determination systems
- G01P 5/06: using rotation of vanes (measuring speed of rotating shafts G01P3/00)
- G01S 13/951: {ground based}
- G01S 15/58: Velocity or trajectory determination systems; Sense-of-movement determination systems {(velocity measurement in imaging systems G01S15/8979)}
- G01S 15/885: {Meteorological systems}
- G01S 17/58: Velocity or trajectory determination systems; Sense-of-movement determination systems
- G01S 17/95: for meteorological use
- F03D 7/02: the wind motors having rotation axis substantially parallel to the air flow entering the rotor
- F03D 17/00: Monitoring or testing of wind motors, e.g. diagnostics (testing during commissioning of wind motors F03D13/30)
- F05B 2260/84: Modelling or simulation
- F05B 2270/32: Wind speeds
- F05B 2270/8042: Lidar systems
- G01S 17/894: Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar
- Y02A 90/10: Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- F03D: WIND MOTORS
- F05B: INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE

## Abstract

A wind flow sensing system for determining a turbulence of wind flow at a set of different altitudes above a terrain is provided. The wind flow sensing system comprises an input interface configured to receive a set of measurements of radial velocities at line-of-site points above the terrain for each of the altitudes for a set of time steps, and a processor configured to estimate velocity fields for each of the altitudes based on data assimilation of the velocity fields, estimate unbiased horizontal velocities at each of the altitudes and for each time step, determine an average of the unbiased horizontal velocities for a period of time including the set of time steps, and determine, at each of the altitudes, a turbulence based on the unbiased horizontal velocities for each time step and the average of the unbiased horizontal velocity.

## Claims

### Claim 1

A wind flow sensing system for determining a turbulence of wind flow at a set of different altitudes above a terrain from a set of measurements of radial velocities at each of the altitudes, comprising:
an input interface configured to receive the set of measurements of radial velocities at line-of-site points above the terrain for each of the altitudes for a set of time steps;
a processor configured to:
estimate velocity fields for each of the altitudes based on data assimilation of the velocity fields above the terrain to fit the measurements of radial velocities, wherein the velocity fields are estimated for the set of time steps;
estimate unbiased horizontal velocities at each of the altitudes and for each time step as a horizontal projection of the corresponding radial velocities corrected with corresponding horizontal derivatives of vertical velocities of the estimated velocity fields determined for the corresponding time step;
determine, at each of the altitudes, an average of the unbiased horizontal velocities for a period of time including the set of time steps; and
determine, at each of the altitudes, a turbulence based on the unbiased horizontal velocities for each time step and the average of the unbiased horizontal velocity; and
an output interface configured to render the turbulence at each of the altitudes.

### Claim 2 (depends on 1)

The wind flow sensing system of claim 1, wherein the data assimilation is performed by simulating computational fluid dynamics (CFD) of the wind flow or by analytical fluid mechanics approximation using potential flow approximation.

### Claim 3 (depends on 2)

The wind flow sensing system of claim 2, wherein the processor is configured to:
determine boundary conditions for an inlet velocity field;
perform the simulation of the CFD by solving Navier-Stokes equations defining the wind flow with the boundary conditions; and
update the boundary conditions and repeat the simulation until a termination condition is met.

### Claim 4 (depends on 2)

The wind flow sensing system of claim 2, wherein the processor is configured to:
approximate a non-convex shape of the terrain using a set of convex shapes;
determine boundary conditions for an inlet velocity field;
derive analytical solution of Laplacian equations defining the wind flow with the boundary conditions; and
update the boundary conditions and repeat the simulation until a termination condition is met.

### Claim 5 (depends on 1)

The wind flow sensing system of claim 1, wherein the turbulence includes an intensity of the turbulence determined according to a ratio of root-mean-square of turbulent velocity fluctuations over the average unbiased horizontal velocity.

### Claim 6 (depends on 1)

The wind flow sensing system of claim 1, wherein the turbulence includes kinetic energy of the turbulence determined according to half of sum of root-mean-square of the turbulent velocity fluctuations.

### Claim 7 (depends on 1)

The wind flow sensing system of claim 1, wherein the period of time is multiple of 10 minutes and difference between time steps is multiple of a second.

### Claim 8 (depends on 1)

The wind flow sensing system of claim 1, further comprising:
a memory configured to store a correction function trained to correct the unbiased horizontal velocities, wherein the processor applies the correction function to correct the unbiased horizontal velocities before estimating the turbulence.

### Claim 9 (depends on 8)

The wind flow sensing system of claim 8, wherein the correction function is trained to reduce a difference between ground truth and the unbiased horizontal velocities determined based on simulating computational fluid dynamics (CFD) of the wind flow by solving Navier-Stokes equations.

### Claim 10 (depends on 8)

The wind flow sensing system of claim 8, wherein the correction function is trained to reduce a difference between ground truth and the unbiased horizontal velocities determined based on analytical solution of Laplacian equations defining the wind flow over an approximated terrain.

### Claim 11 (depends on 1)

The wind flow sensing system of claim 1, further comprising a controller of a wind turbine to control the wind turbine based on one or more of the estimated unbiased horizontal velocities at each of the altitudes, or the turbulence at each of the altitudes, wherein the wind turbine is operatively connected to the wind flow sensing system of claim 1.

### Claim 12

A wind flow sensing method for determining a turbulence of wind flow at a set of different altitudes above a terrain from a set of measurements of radial velocities at each of the altitudes, wherein the method uses a processor coupled with stored instructions implementing the method, wherein the instructions, when executed by the processor carry out steps of the method, comprising:
receiving the set of measurements of radial velocities at line-of-site points above the terrain for each of the altitudes for a set of time steps;
estimating velocity fields for each of the altitudes based on data assimilation of the velocity fields above the terrain to fit the measurements of radial velocities, wherein the velocity fields are estimated for the set of time steps;
estimating unbiased horizontal velocities at each of the altitudes and for each time step as a horizontal projection of the corresponding radial velocities corrected with corresponding horizontal derivatives of vertical velocities of the estimated velocity fields determined for the corresponding time step;
determining, at each of the altitudes, an average of the unbiased horizontal velocities for a period of time including the set of time steps; and
determining, at each of the altitudes, a turbulence based on the unbiased horizontal velocities for each time step and the average of the unbiased horizontal velocity; and
outputting the turbulence at each of the altitudes.

### Claim 13 (depends on 12)

The wind flow sensing method of claim 12, wherein the data assimilation is performed by simulating computational fluid dynamics (CFD) of the wind flow or by analytical fluid mechanics approximation using potential flow approximation.

### Claim 14 (depends on 12)

The wind flow sensing method of claim 12, wherein the turbulence includes an intensity of the turbulence determined according to a ratio of root-mean-square of turbulent velocity fluctuations over the average unbiased horizontal velocity.

### Claim 15 (depends on 12)

The wind flow sensing method of claim 12, wherein the turbulence includes kinetic energy of the turbulence determined according to half of sum of root-mean-square of the turbulent velocity fluctuations.